Integration tests: RDM, Rules approval and silver writer on the shared pg16 server

[paulananth]

What

test_rdm_postgres.py, test_rules_approval_postgres.py and test_silver_writer_postgres.py each started their own Docker postgres:16-alpine container with their own readiness loop. They now use the shared tests/support/pg16.server(), as the clean MDM integration tests already do (#900).

pg16.server() uses Docker in CI and PG16_SERVER=pgserver locally. It yields the server only once it answers SELECT 1, and cleans up either way.

The silver writer test still accepts PG16_ADMIN_URL, for a server kept between runs.

This was a follow-up from the GoF review on #900. The change is test-only: 35 lines added, 84 removed.

Checked

• 23 passed on a local PostgreSQL 16, in 65 s, with PG16_SERVER=pgserver uv run --with pgserver pytest tests/integration/test_rdm_postgres.py tests/integration/test_rules_approval_postgres.py tests/integration/test_silver_writer_postgres.py.
• ruff --select F is clean.
• CI runs the same tests on Docker.

Review (Standards, Spec, GoF)

• No hard violations. GoF: leave the structure as is.
• Fixed: docker() and IMAGE in test_clean_mdm_postgres.py had no caller left once the silver writer test moved, so they are deleted. 57 clean MDM and silver writer tests pass on local PostgreSQL 16.
• Noted, not changed:
  • Fixture errors: a server that never becomes ready now raises pg16's RuntimeError (a fixture error) instead of pytest.fail.
  • Docker image: the Rules approval test now needs the image present, as the others already did. CI pulls it before the integration tests.
  • Remaining Docker setup: tests/engine/test_data_skill_bundle_postgres.py still starts its own container. It is on Codex's path list, so it is left as a follow-up.

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https://claude.ai/code/session_01FFKdv4nqKXKM9d5Cf2hEFk